title: Iodoalkoxylation of 1,5-anhydro-2-deoxy-hex-1-enitols (glycals).
abstract: Exclusive trans-addition is observed in the iodoalkoxylation of the 6-membered cyclic enol ethers 3,4-di-O-acetyl-L-rhamnal (1), 3,4-di-O-acetyl-L-fucal (2), and related glycal derivatives. The main products from 1 and from 3,4,6-tri-O-acetyl-D-glucal (3) thus had the alpha-manno configuration. Similarly, alpha-talo products were obtained from 2 in 87-93% yield. The product distribution is not affected by the electronegativity of the 5-substituent. It is concluded that steric factors in the glycal and the nucleophile affect only the step of trans-diaxial opening of the intermediate iodonium ion. Enhanced yields of the desired trans-diaxial products were observed in reactions of glycals having the lyxo configuration when the reactions were conducted in tetrahydrofuran or methanol.
authors.affiliation: Department of Chemistry, Ohio State University, Columbus 43210.
authors.forename: D
authors.initials: D
authors.lastname: Horton
authors.forename: W
authors.initials: W
authors.lastname: Priebe
authors.forename: M
authors.initials: M
authors.lastname: Sznaidman
mesh_terms: D000478:Alkylation; D003837:Deoxy Sugars / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism; D013402:Sugar Alcohols / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D003837:Deoxy Sugars; D013402:Sugar Alcohols